The wide spread of mobile terminal equipment, such as mobile phones for example, requires rapid data transmission by means of wireless interfaces and wireless local data networks. Light emitting diodes (LEDs) can be used in buildings for illuminating rooms. Light emitting diodes are distinguished by low energy consumption, relatively long life and good scalability. For illuminating rooms in buildings, light emitting diodes provided therein are dimmed in order to be able to adjust the illumination level within a room according to the particular requirements.